Battery

ABSTRACT

A battery includes an electrolyte disposed on a substantially planar substrate. The electrolyte has a first surface extending from the substrate and in contact with a cathode. The electrolyte has a second surface extending from the substrate and in contact with an anode. The second surface is opposite the first surface. The anode and the cathode are non-overlapping. The battery additionally includes a biocompatible protective layer that covers the electrolyte and at least portions of the anode and cathode. The battery can be disposed in an eye-mountable device or other device to power electronics in the device. The battery can be configured to be rechargeable.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/163,663, filed Jan. 24, 2014, which application is incorporatedherein by reference.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

The rise to ubiquity of small, battery-powered devices is due in part toadvances in battery technology. Advances in battery technology haveenabled the fabrication of tiny, high-energy-density electrochemicalbatteries capable of powering advanced devices for extended periods oftime while occupying small volumes. An electrochemical battery comprisesan electrolyte interposed between two electrodes (an anode and acathode). Electrochemical reactions between the anode and theelectrolyte and between the electrolyte and the cathode can cause thedevelopment of an electrical potential between the electrodes. Continuedelectrochemical reactions could drive an electrical current from oneelectrode, through a device connected to the electrodes, to the oppositeelectrodes, allowing the device to perform some function using theelectrical current.

SUMMARY

Some embodiments of the present disclosure provide a battery including:a substrate, wherein the substrate is substantially planar; anelectrolyte disposed on the substrate, wherein the electrolyte has afirst surface extending from the substrate and a second surfaceextending from the substrate and opposite the first surface; a cathodedisposed on the substrate and in contact with the first surface of theelectrolyte; an anode disposed on the substrate and in contact with thesecond surface of the electrolyte, wherein the anode and cathode arenon-overlapping; and a biocompatible protective layer, wherein thebiocompatible protective layer covers the electrolyte and at leastportions of the cathode and anode.

Some embodiments of the present disclosure provide a body mountabledevice including: a shaped polymeric material; and a battery embeddedwithin the shaped polymeric material. The battery can include asubstrate, wherein the substrate is substantially planar; an electrolytedisposed on the substrate, wherein the electrolyte has a first surfaceextending from the substrate and a second surface extending from thesubstrate and opposite the first surface; a cathode disposed on thesubstrate and in contact with the first surface of the electrolyte; ananode disposed on the substrate and in contact with the second surfaceof the electrolyte, wherein the anode and cathode are non-overlapping;and a biocompatible protective layer, wherein the biocompatibleprotective layer covers the electrolyte and at least portions of thecathode and anode.

Some embodiments of the present disclosure provide a method including:forming a substrate, wherein the substrate is substantially planar;forming an electrolyte on the substrate, such that the electrolyte has afirst surface extending from the substrate and a second surfaceextending from the substrate and opposite the first surface; forming acathode on the substrate, such that the cathode is in contact with thefirst surface of the electrolyte; forming an anode on the substrate,such that the anode is in contact with the second surface of theelectrolyte, and the anode and cathode are non-overlapping; and forminga biocompatible protective layer, such that the biocompatible protectivelayer covers the electrolyte and at least portions of the cathode andanode.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are perspective and cross-sectional views of batteriesdisposed on substrates.

FIGS. 2A-2E are perspective views of batteries disposed on substrates.

FIG. 3A is a bottom view of an example eye-mountable device.

FIG. 3B is an aspect view of the example eye-mountable device shown inFIG. 3A.

FIG. 3C is a side cross-section view of the example eye-mountable deviceshown in FIGS. 3A and 3B while mounted to a corneal surface of an eye.

FIG. 3D is a close-in side cross-section view of the exampleeye-mountable device shown in FIGS. 3A and 3B while mounted to a cornealsurface of an eye.

FIG. 4 is a flowchart of an example method.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying figures, which form a part hereof. In the figures, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, figures, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the scope of the subject matter presented herein. It willbe readily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

I. Overview

An electrochemical battery can comprise an electrolyte interposedbetween two electrodes (an anode and a cathode) arranged on oppositesurfaces of the electrolyte. The energy capacity of the battery can berelated to the total volume of the electrolyte. As such, increasing thearea of the electrodes and/or increasing the thickness of theelectrolyte between the electrodes can increase the energy capacity ofthe battery. The thickness of an effective battery can be limited bydiffusion in the electrolyte or by other chemical processes occurring inthe electrolyte and/or electrodes such that the capacity of the batterycannot be increased by an increase of thickness beyond an effectivemaximum thickness. The battery can be fabricated on a substrate, and canfurther include a biocompatible protective layer to prevent degradationof the battery by substances in the environment of the battery.

As illustrated in FIG. 1A, an example electrochemical battery 100 acould be fabricated by disposing, on a substantially planar substrate110 a, layers parallel to the substrate 110 a including a cathode 130 a,an electrolyte 120 a, an anode 140 a, and a biocompatible protectivelayer 150 a. The battery could be electronically coupled to othercomponents by interconnects 160 a, 165 a. An energy capacity of thebattery 100 a could be increased by increasing the area of the layers(i.e., the cathode 130 a, anode 140 a, electrolyte 120 a, andbiocompatible protective layer 150 a) and/or by increasing the thickness(defined as a measurement in the vertical direction 170 a) of theelectrolyte 120 a (up to a diffusion-limited maximum thickness). Thelayers 120 a, 130 a, 140 a, 150 a could have minimum thicknesses(measured in the vertical direction 170 a) determined by functionaland/or fabrication limitations. For example, the anode 140 a and/orcathode 130 a could have minimum thicknesses to ensure adequateconduction. For example, a method used to deposit the anode 140 a and/orcathode 130 a could have a minimum deposited layer thickness. As aresult, the battery 100 a fabricated from layers 120 a, 130 a, 140 a,150 a formed atop a substrate 110 a such that the layers 120 a, 130 a,140 a, 150 a were parallel to the substrate 110 a could have a minimumoverall thickness that was the sum of the minimum thicknesses of thelayers (including a minimum thickness of the substrate 110 a, thecathode 130 a, the anode 140 a, the electrolyte 120 a, and thebiocompatible protective layer 150 a).

In some applications, it may desirable to provide a battery that has athickness that is less than a specified maximum thickness. For example,in the case of a battery that is to be included in an eye-mountabledevice, it may be desirable for the battery to have a thickness lessthan a fraction of the thickness of the eye-mountable device. In someinstances, the application-specific maximum thickness could be less thanthe minimum overall thickness of a battery fabricated from layers formedatop a parallel substantially planar substrate as described above. Insuch instances, a different battery configuration could be used, forexample, as illustrated in FIGS. 1B-D and described below.

FIG. 1B illustrates in cross section an example electrochemical battery100 b that could be fabricated by disposing, on a substantially planarsubstrate 110 b, an electrolyte 120 b having a first surface 135 b and asecond surface 145 b extending from the substrate 110 b. The secondsurface 145 b could be opposite the first surface 135 b. The batterycould additionally include a cathode 130 b that is in contact with thefirst surface 135 b of the electrolyte 120 b, an anode 140 b that is incontact with the second surface 145 b of the electrolyte 120 b, and abiocompatible protective layer 150 b. With this configuration, cathode130 b and anode 140 b are non-overlapping over 110 b. The battery 100 bcould be electronically coupled to other components by interconnects 160b, 165 b.

The anode 140 b, electrolyte 120 b, and cathode 130 b could have minimumwidths (defined as a measurement in the horizontal direction 180 b). Asthe widths of the anode 140 b, electrolyte 120 b, and cathode 130 b areperpendicular to the overall thickness of the battery 100 b (the overallthickness of the battery 100 b being defined as a measurement in thevertical direction 170 b), the battery 100 b can have a minimum overallthickness that is not constrained by the minimum widths of the anode 140b, electrolyte 120 b, and cathode 130 b. The overall thickness of thebattery 100 b is instead defined by respective thicknesses of thesubstrate 110 b, the biocompatible protective layer 150 b, and athickest portion (defined in the vertical direction 170 b) of the anode140 b, electrolyte 120 b, and cathode 130 b between the substrate 110 band the biocompatible protective layer 150 b.

The thickest portion of the anode 140 b, electrolyte 120 b, and cathode130 b between the substrate 110 b and the biocompatible protective layer150 b could be chosen such that the overall thickness of the battery isless than a maximum thickness (e.g., 50 microns) according to anapplication. The energy capacity of the battery 100 b could be increasedby increasing the area of the first surface 135 b and/or second surface145 b while keeping the thickest portion of the anode 140 b, electrolyte120 b, and cathode 130 b between the substrate 110 b and thebiocompatible protective layer 150 b below a chosen maximum according toan application.

A biocompatible protective layer (e.g., biocompatible layer 150 b inbattery 100 b) could be configured to prevent the environment of abattery from degrading the function of the battery. For example, anelectrolyte of the battery could be degraded by moisture or otherelements in the environment of the battery. The biocompatible protectivelayer could be disposed to cover the electrolyte and at least portionsof an anode and a cathode of the battery adjacent to the electrolytesuch that the biocompatible protective layer formed a barrier thatprevented moisture or other elements of the environment from interactingwith and/or degrading the electrolyte. For example, the biocompatibleprotective layer could be a layer of parylene deposited onto thesubstrate, anode, cathode, and/or electrolyte and cured to form abiocompatible moisture barrier.

A biocompatible protective layer covering part or all of a battery couldbe configured to be in some way biocompatible. That is, thebiocompatible protective layer could be composed of a material and/orinclude a surface treatment or coating such that it was able to bedisposed in a biological environment for a period of time withoutsubstantially negatively impacting the function of biological structuresin the biological environment. For example, the biocompatible protectivelayer could be configured such that, when a battery or other objectpartially or wholly covered by the biocompatible protective layer wasimplanted in biological tissue, the biological tissue was substantiallyable to continue functioning despite the presence of the battery orother device implanted in the biological tissue. In some examples, thebiocompatible protective layer could be configured such that, when abattery or other object partially or wholly covered by the biocompatibleprotective layer was disposed on an eye, the eye was substantially ableto continue functioning and the eye exhibited substantially no allergicor inflammatory response to the presence of the battery or other objecton the eye.

A substrate (e.g., substrate 110 b in battery 100 b) can be used toprovide support for a battery, to integrate the battery into a device,and/or to provide a structure during fabrication of the battery. Thesubstrate could be a material capable of withstanding high temperatures,high pressures, oxidizing environments, or other conditions associatedwith fabrication or operation of the battery. The substrate materialcould be chosen such that other aspects of a device including thebattery (for example, electronics) could be formed on the substrate atthe same time as or at a different time than the formation of an anode,a cathode, an electrolyte, and/or a biocompatible protective layer ofthe battery on the substrate. The substrate material could be chosensuch that fabrication of the battery could be achieved using techniquesand processes used for fabrication of integrated circuit devices. Thesubstrate material could be glass, silicon, diamond, silicon carbide, orsome other material according to an application. The substrate materialcould extend beyond components of the battery (e.g., anode, cathode, andelectrolyte) or could only be large enough to underlay the components ofthe battery.

An electrolyte of a battery could include a variety of chemicals orcombinations of chemicals configured in a variety of ways. Theelectrolyte could include amorphous, crystalline, polycrystalline,and/or polymeric solid or gel components. The electrolyte also couldinclude liquid components. The electrolyte could include organic and/orinorganic salts, metallic or nonmetallic ions, solvents, dissolvedgases. Some components (e.g., salts) could be dissolved or otherwiseincorporated in other components of the electrolyte (e.g., a flexiblelattice of a gel polymer, a solid polymer, or a ceramic). In oneexample, the electrolyte is a gel electrolyte and the gel electrolyteincludes polyacrylonitrile, propylene carbonate, ethylene carbonate, andzinc trifluoromethane sulfonate. However, other electrolyte chemistriesand configurations could be used as well.

The configuration of electrodes (e.g., a cathode and an anode) of abattery could be related to the composition of an electrolyte of thebattery. For example, a surface of a cathode in contact with a firstsurface of an electrolyte containing zinc trifluoromethane sulfonatecould include manganese oxide. The cathode could be wholly composed ofmanganese oxide, or could only be composed of manganese oxide on thesurface in contact with the first surface of the electrolyte (depositedon another metal comprising the remainder of the anode, or an oxideformed on a manganese-metal surface of the cathode through an oxidizingstep). For example, a surface of an anode in contact with a secondsurface of an electrolyte containing zinc trifluoromethane sulfonatecould include zinc metal. The anode could be wholly composed of zincmetal, or could only be composed of zinc metal on the surface in contactwith the second surface of the electrolyte (deposited on another metalcomprising the remainder of the anode, or a zinc foil formed on theremainder of the anode). The geometry of a battery could be related tothe configuration of electrodes and an electrolyte of the battery. Forexample, the electrolyte could include zinc trifluoromethane sulfonate,a surface of the cathode in contact with a first surface of theelectrolyte could include manganese oxide, a surface of the anode incontact with a second surface of the electrolyte could include zincmetal, and the first and second surfaces of the electrolyte could beless than about 100 microns apart. A distance between a first surface ofan electrolyte and a second surface of an electrolyte could be chosen tomaximize an energy capacity of a battery, to maximize a power capacityof a battery, or to optimize other properties or combinations ofproperties of a battery according to an application.

A battery could assume many shapes while including an electrolyte havingfirst and second surfaces extending from a substantially planarsubstrate, a non-overlapping cathode and anode in contact with the firstand second surfaces, respectively, and a biocompatible protective layer.FIG. 1B illustrates an example battery 100 b that has an electrolyte 120b that is disposed as a substantially straight shape such that the firstand second surfaces 135 b, 145 b are substantially planar. FIG. 1C is across-sectional illustration of an example electrochemical battery 100 cthat includes a substantially planar substrate 110 c and an electrolyte120 c having a first surface 135 c and a second surface 145 c extendingfrom the substrate 110 c. The second surface 145 c is opposite the firstsurface 135 c. The electrolyte 120 c has a curved shape such that thefirst and second surfaces 135 c, 145 c are curved surfaces. The batteryadditionally includes a cathode 130 c (that is in contact with the firstsurface 135 c of the electrolyte 120 c), an anode 140 c (that does notoverlap the cathode 130 c and that is in contact with the second surface145 c of the electrolyte 120 c), and a biocompatible protective layer150 c. The battery 100 c could be electronically coupled to othercomponents by interconnects 160 c, 165 c.

Other embodiments of electrochemical batteries could have electrolyteswith different shapes and concomitant shapes of first and secondsurfaces according to an application. In some examples, the electrolytecould have a closed shape. For example, the electrolyte could form aclosed loop or ellipse. Additionally or alternatively, the electrolytecould have a spiral, branching, and/or space-filling shape. Thus, theelectrolyte could have multiple ‘first surfaces’ and multiple ‘secondsurfaces’ such that first and second surfaces are locally substantiallyopposite. Additional configurations of an electrochemical battery areanticipated.

An electrochemical battery could include more than one electrochemicalcell, where an electrochemical cell includes an electrolyte and acathode and an anode in contact with surfaces of the electrolyte. FIG.1D is a cross-sectional illustration of an example electrochemicalbattery 100 d that includes a substantially planar substrate 110 d and afirst cell that includes a first electrolyte 120 d having a firstsurface 135 d and a second surface 145 d extending from the substrate110 d. The second surface 145 d is opposite the first surface 135 d. Thefirst electrolyte 120 d has a curved shape such that the first andsecond surfaces 135 d, 145 d are curved surfaces. The first celladditionally includes a first cathode 130 d (that is in contact with thefirst surface 135 d of the first electrolyte 120 d), and a first anode140 d (that does not overlap the first cathode 130 d and that is incontact with the second surface 145 d of the first electrolyte 120 d).The battery 100 d further includes a second cell that includes a secondelectrolyte 122 d having a first surface 137 d and a second surface 147d extending from the substrate 110 d. The second surface 147 d isopposite the first surface 137 d. The second electrolyte 122 d has acurved shape such that the first and second surfaces 137 d, 147 d arecurved surfaces. The second cell additionally includes a second cathode132 d (that is in contact with the first surface 137 d of the secondelectrolyte 122 d), and a second anode 142 d (that does not overlap thesecond cathode 132 d and that is in contact with the second surface 145d of the second electrolyte 122 d). The anode 140 d of the first celland the cathode 132 d of the second cell are separated by a barrier 170d. The battery 100 d additionally includes a biocompatible protectivelayer 150 d that covers the first and second electrolytes 120 d, 122 dand at least portions of the first and second cathodes 130 d, 132 d andfirst and second anodes 140 d, 142 d. The battery 100 d could beelectronically coupled to other components by interconnects 160 d, 165d.

The arrangement, shape, and number of cells in the example battery 100 dare meant as illustrative, non-limiting examples. It is anticipated thata battery could include more than two cells. The shape of the cellscould be straight, curved, branching, looped, or some otherconfiguration. The cells of a battery could be configured to be roughlyparallel (as in the example battery 100 d) or could be arranged relativeto each other in other ways. The cells could be similarly configured(e.g., similar anode materials, similar cathode materials, similarelectrolyte composition, similar electrolyte height, similarcathode-anode separation distance) or could be differently configuredaccording to an application. For example, a first cell of a batterycould be configured to provide high energy capacity but low powercapacity. A second cell of the battery could be differently configuredto provide high power capacity but low energy capacity.

Cells of an electrochemical battery could be electrically interconnectedin a variety of ways. For example, the barrier 170 d of the examplebattery 100 d could be a conductor, such that the first anode 140 d ofthe first cell of the battery 100 d is electrically connected to thesecond cathode 132 d of the second cell of the battery 100 d. The cellsof the battery 100 d could be described as being connected in series inthis example. A voltage produced by the battery 100 d between the firstcathode 130 d and the second anode 142 d (which could be accessed usinginterconnects 160 d, 162 d) could correspond to the sum of respectivevoltages produced by the first and second cells of the battery 100 d.Alternatively, the cells could be connected some other way. For example,the barrier 170 d could include an electrical insulator, the first andsecond cathodes 130 d, 132 d could be electrically connected, and thefirst and second anodes 140 d, 142 d could be electrically connected.The cells of the battery 100 d could be described as being connected inparallel in this example. A current capacity of the battery 100 d couldcorrespond to the sum of respective current capacities of the first andsecond cells of the battery 100 d. Other interconnections betweenelectrochemical cells are possible as well.

Individual cells or sets of cells of an electrochemical battery could beoperated in series, in parallel, or according to some otherconfiguration. Individual cells or sets of cells of an electrochemicalbattery could additionally or alternatively be operated (e.g.,recharged, discharged) individually. For example, individual cells of abattery could be individually recharged and/or discharged according to awear leveling algorithm, a load balancing algorithm, or some otherapplication.

II. Example Batteries

In some embodiments, an electrochemical battery includes a substantiallyplanar substrate, an electrolyte disposed on the substrate havingopposite first and second surfaces that extend from the substrate, acathode disposed on the substrate and in contact with the first surfaceof the electrolyte, an anode disposed on the substrate and in contactwith the second surface of the electrolyte, and a biocompatibleprotective layer that covers the electrolyte and at least portions ofthe cathode and anode. A wide variety of compositions and configurationsof the substrate, electrode, anode, cathode, and biocompatibleprotective layer are possible. Such a battery could be disposed in avariety of systems or devices according to a variety of applications.

FIG. 2A illustrates an example electrochemical battery 200 a. Thebattery 200 a includes a substantially planar substrate 210 a, anelectrolyte 220 a disposed on the substrate 210 a, a cathode 230 adisposed on the substrate 210 a, an anode 240 a disposed on thesubstrate 210 a, and a biocompatible protective layer 250 a disposed tocover the electrolyte 220 a and at least a portion of both the cathode230 a and the anode 240 a. The electrolyte 220 a has a first surface 235a and a second surface 245 a extending from the substrate 210 a. Thesecond surface 245 a is opposite the first surface 235 a. The cathode230 a is in contact with the first surface 235 a of the electrolyte 220a and the anode 240 a does not overlap the cathode 230 a and is incontact with the second surface 245 a of the electrolyte 220 a.

In the example battery 200 a of FIG. 2A, the substrate 210 a extendsonly as far as the extent of the overlaying electrolyte 220 a, cathode230 a, and anode 240 a. However, it is possible for a substrate of anelectrochemical battery to extend beyond the extent of electrolytes,cathodes, anodes, and/or biocompatible protective layers disposed on thesubstrate. For example, the substrate could include extensionsconfigured to allow the battery to be mounted on or in another device.For example, the substrate could include tabs or holes for mounting thebattery using adhesives, bolts, tabs, pins, or other methods.

The anode and cathode of an electrochemical battery, for example battery200 a, could be electrically connected to some other system by a varietyof methods. Exposed areas of both the anode and cathode could beconfigured such that electrical connections could be made to them. Forexample, the exposed areas could be configured such that and electricalconnection could be welded, soldered, press-fit, spring-loaded, orotherwise connected to the anode and/or cathode. Additionally oralternatively, the substrate could include electrical traces,connections, or wires configured to electrically connect to the anodeand cathode and to facilitate the electrical connection of the anode andcathode to other devices or systems. The other devices or systems couldinclude electronics disposed, deposited, and/or formed on the substratebefore, during, or after the formation of the anode, cathode,electrolyte, and/or biocompatible protective layer on the substrate.

As shown in FIG. 2A, the biocompatible protective layer 250 a isdisposed to cover the electrolyte 220 a and at least a portion of boththe cathode 230 a and the anode 240 a. In the example of FIG. 2A, thisincludes the biocompatible protective layer 250 a covering surfaces ofthe electrolyte 220 a that are not covered by the substrate 210 a, thecathode 230 a or the anode 240 a (i.e., a front surface 225 a, a topsurface 227 a, and a back surface (not shown)) and a portion of surfacesof the anode 240 a, cathode 230 a, and substrate 210 a that are adjacentto the uncovered surfaces of the electrolyte 120 a (i.e., the frontsurface 225 a, the top surface 227 a, and the back surface).

This disposition of a biocompatible protective layer of a battery ismeant as an exemplary embodiment and is not meant to be limiting. Abiocompatible protective layer could be disposed to completely cover abattery (covering all exposed surfaces of an anode, a cathode, and asubstrate in addition to exposed surfaces of the electrolyte). In someexamples, additional components (e.g., electronics, a second electrolytelayer, conductive traces) could be disposed on a substrate, and thebiocompatible protective layer could be disposed to partially orcompletely cover some or all of the additional components disposed onthe substrate. An adhesion promoter (e.g., a silane) could be disposedon metal components of a battery to enhance the adhesion of componentsof a biocompatible protective layer to the metal components.Additionally or alternatively, a battery (including a substrate, anelectrolyte, an anode and a cathode) could be disposed on some otherbase material. A biocompatible protective layer could then be disposedto cover the electrolyte, at least portions of the anode and thecathode, and all or part of the base material and/or any othercomponents (e.g., electronics, conductive traces) disposed on the basematerial.

An electrochemical battery, like the battery 200 a illustrated in FIG.2A, could be described as containing cells. A cell could include anelectrolyte, a cathode in contact with the electrolyte, and an anode incontact with the electrolyte and not in contact with the cathode. Thebattery 200 a illustrated in FIG. 2A includes one cell. The one cell ofthe battery 200 a includes the electrolyte 220 a, the cathode 230 a, andthe anode 240 a. An electrochemical battery could contain one cell ormore than one cell. Further, the more than one anode and more than onecathode of the more than one cells could be electrically connected toeach other and to other systems or devices in a variety of ways.

FIG. 2B illustrates an example electrochemical battery 200 b thatincludes three cells. The battery 200 b includes a substantially planarsubstrate 210 b, a first cell (including a first electrolyte 220 b, afirst cathode 230 b, and a first anode 240 b all disposed on thesubstrate 210 b), a second cell (including a second electrolyte 222 b, asecond cathode 232 b, and a second anode 242 b all disposed on thesubstrate 210 b), and a third cell (including a third electrolyte 224 b,a third cathode 234 b, and a third anode 244 b all disposed on thesubstrate 210 b). The electrolytes 230 b, 232 b, 234 b have respectivefirst surfaces 235 b, 237 b, 239 b and second surfaces 245 b, 247 b, 249b extending from the substrate 210 b with respective second surfaces 245b, 247 b, 249 b being opposite respective first surfaces 235 b, 237 b,239 b. Respective cathodes 230 b, 232, 234 b are in contact withrespective first surfaces 235 b, 237 b, 239 b and respective anodes 240b, 242 b, 244 b are in contact with respective second surfaces 245 b,247 b, 249 b. The battery 200 b includes barriers 270 b, 272 b that aredisposed between the first and second cells and between the second andthird cells, respectively. The battery 200 b further includes abiocompatible protective layer 250 b disposed to cover the electrolytes220 b, 222 b, 224 b and at least a portion of both the cathodes 230 b,232 b, 234 b and the anodes 240 b, 242 b, 244 b.

The cells of the battery 200 b could be connected to each other and toother systems or devices in various ways according to an application. Insome examples, the barriers 270 b, 272 b could include conductors, suchthat the cells could be described as being connected in series. In suchexamples, a voltage could appear between the first cathode 230 b and thethird anode 244 b corresponding to the sum of the voltages produced bythe three cells of the battery 200 b. In some examples, one or both ofthe barriers 270 b, 272 b could include insulators, and the three cellscould be electrically connected in parallel. Other connections of thecells to each other and to other systems or devices are anticipated.

While the example batteries 200 a, 200 b illustrate example electrolyteshaving substantially straight shapes, other configurations ofelectrolytes, anodes, cathodes, substrates, and biocompatible protectivelayers are anticipated. For example, the one or more electrolytes couldbe curved shapes, closed loops, branching structures, space-fillingcurves, angular shapes, and/or other configurations according to anapplication.

FIG. 2C illustrates an example electrochemical battery 200 c thatincludes an electrolyte 220 c configured to have an angled spiral shape.The battery 200 c includes a substantially planar substrate 210 c, theelectrolyte 220 c disposed on the substrate 210 c, a cathode 230 cdisposed on the substrate 210 c, an anode 240 c disposed on thesubstrate 210 c, a barrier 270 c, and a biocompatible protective layer250 c disposed to cover the electrolyte 220 c and at least a portion ofboth the cathode 230 c and the anode 240 c. The electrolyte 220 c has afirst surface 235 c and a second surface 245 c extending from thesubstrate 210 c. The second surface 245 c is opposite the first surface235 c. The cathode 230 c is in contact with the first surface 235 c ofthe electrolyte 220 c and the anode 240 c does not overlap the cathode230 c and is in contact with the second surface 245 c of the electrolyte220 c.

Note that the distance between an example point on the first surface 235c and an opposite point on the second surface 245 c is not constant forthe example angled spiral shaped battery 200 c illustrated in FIG. 2C.For example, the distance between a point on the first surface 235 cthat is on one of the corners of the first surface 235 c and an oppositepoint on an opposite corner of the second surface 245 c could be greaterthan the distance between other sets of corresponding opposite points onthe first and second surfaces 235 c, 245 c. Other angled electrolytes orelectrolytes having other shapes could have similarly varying distancesbetween points on a first surface of the electrolyte and correspondingpoints on an opposite second surface of the electrolyte.

An electrolyte could be configured to have an angled spiral shape toincrease a volume of electrolyte, an area of a first and/or secondsurface of the electrolyte, to increase an energy or a current capacityof a battery, or to optimize some other factor. For example, the battery200 c of FIG. 2C could have been configured with an angled spiral shapeto attain an increased energy capacity while having a substrate size andshape equal to the size and shape of the substrate 210 c. Othermotivations or design considerations are anticipated according to anapplication. Further, an electrochemical battery having a firstelectrolyte configured to have an angled spiral shape could includemultiple electrolytes (and corresponding anodes, cathodes, and first andsecond surfaces) that could be disposed adjacent to the firstelectrolyte such that the electrolytes form a multiple spiral or someother interlocking shape or shapes.

FIG. 2D illustrates an example electrochemical battery 200 d having anelectrolyte 220 d configured as a closed loop. The battery 200 dincludes a substantially planar substrate 210 d, the electrolyte 220 ddisposed on the substrate 210 d, a cathode 230 d disposed on thesubstrate 210 d, an anode 240 d disposed on the substrate 210 d, and abiocompatible protective layer 250 c disposed to cover the electrolyte220 d and at least a portion of both the cathode 230 d and the anode 240d. The electrolyte 220 d has a first surface 235 d and a second surface245 d extending from the substrate 210 d. The second surface 245 d isopposite the first surface 235 d. The cathode 230 d is in contact withthe first surface 235 d of the electrolyte 220 d and the anode 240 ddoes not overlap the cathode 230 d and is in contact with the secondsurface 245 c of the electrolyte 220 d.

The battery 200 d is meant as a non-limiting example embodiment of anelectrochemical battery having a single electrolyte configured as aclosed loop. An electrochemical battery could include multipleelectrolytes (and corresponding anodes, cathodes, and first and secondsurfaces extending from the substrate) configured as a closed loopand/or electrolytes not configured as closed loop. Further, the examplesubstrate 210 d is configured to have a hole corresponding to the middleof the closed loop; in other embodiments, the hole could be closedand/or the substrate could be configured to have some other shape orsize than a closed loop corresponding to the extent of the electrolyte,anode, and cathode disposed on the substrate.

FIG. 2E illustrates an example electrochemical battery 200 e having anelectrolyte 220 e configured to have a spiral shape. The battery 200 eincludes a substantially planar substrate 210 e, the electrolyte 220 edisposed on the substrate 210 e, a cathode 230 e disposed on thesubstrate 210 e, an anode 240 e disposed on the substrate 210 e, abarrier 270 e, and a biocompatible protective layer 250 e disposed tocover the electrolyte 220 e and at least a portion of both the cathode230 e and the anode 240 e. The electrolyte 220 e has a first surface 235e and a second surface 245 e extending from the substrate 210 e. Thesecond surface 245 e is opposite the first surface 235 e. The cathode230 e is in contact with the first surface 235 d of the electrolyte 220e and the anode 240 e does not overlap the cathode 230 e and is incontact with the second surface 245 e of the electrolyte 220 e.

The battery 200 e is meant as a non-limiting example embodiment of anelectrochemical battery having a single electrolyte configured as aspiral. An electrochemical battery could include multiple electrolytes(and multiple corresponding anodes, cathodes, and first and secondsurfaces extending from the substrate) configured as spirals and/orelectrolytes not configured as spirals. Batteries including multipleelectrolytes configured as spirals could have the electrolytesconfigured such that the electrolytes form a multiple spiral or someother interlocking shape or shapes. Further, the example substrate 210 eis configured to have a hole corresponding to the open middle of thespiral; in other embodiments, the hole could be closed and/or thesubstrate could be configured to have some other shape or size than aclosed shape corresponding to the extent of the electrolyte, anode, andcathode disposed on the substrate.

An electrochemical battery could include an electrolyte, an anode, acathode, and/or some other elements configured in a variety of waysaccording to an application. An electrolyte could include a variety ofchemicals. The configuration of different elements of the battery couldbe inter-related; for example, an anode being configured to include zincmetal could be related to an electrolyte containing a zinc salt.Further, the size, shape, distance between elements, or other aspects ofa battery could be inter-related and/or related to the composition ofthe electrolyte, anode, cathode, and/or other components of the battery.In some examples (e.g., the batteries illustrated in FIGS. 2A-2E), abattery could include a gel electrolyte that includes polyacrylonitrile,propylene carbonate, ethylene carbonate, and zinc trifluoromethanesulfonate, an anode that includes zinc metal on a surface of the anodein contact with the electrolyte, and a cathode that include manganeseoxide on a surface of the cathode in contact with the electrolyte.Further, first and second surfaces of the electrolyte could be generallyseparated by a distance of about 100 microns. In examples where theelectrolyte has a more complicated shape (e.g., batteries 200 c, 200 d,200 e illustrated in FIGS. 2C-2E) this could mean that the separationbetween the first and second surfaces of the electrolyte could have arange of values. This distance limit could be determined based on adiffusion rate within the electrolyte or some other considerationaccording to an application.

An electrochemical battery configured as described herein could beincorporated in a variety devices or systems and operated according to avariety of applications. Such batteries could be incorporated intowholly or partially battery-powered devices to power the devices. Thedevices could be implantable devices and/or devices designed tointerface in some way with a body. For example, such batteries could beincorporated into thin devices configured to be mounted onto an eye, atooth, or some other surface of a body to measure some property of thebody and/or to interact with the body. The device could be configured tobe powered by a battery to apply a treatment or pharmaceutical to abody. Such batteries could be incorporated into some other thin device.For example, a battery could be incorporated into a thin adhesive sensorpatch or some other device configured to unobtrusively mount onto asurface and perform some function. Such batteries could be used to powera device having the size and shape of a credit card, a business card, orsome other substantially planar device. A battery could have arechargeable chemistry, and could be operated to alternatively power adevice and to be recharged. A battery could be a primary battery suchthat it was not able to be recharged.

III. Example Body-Mountable Device

FIG. 3A is a bottom view of an example body-mountable device 310. FIG.3B is an aspect view of the example body-mountable device 310 shown inFIG. 3A. It is noted that relative dimensions in FIGS. 3A and 3B are notnecessarily to scale, but have been rendered for purposes of explanationonly in describing the arrangement of the example body-mountable device310. The body-mountable device 310 is formed of a polymeric material 320shaped as a curved disk. A battery 360 is embedded within the polymericmaterial 320 of the body-mountable device 310. In the examplebody-mountable device 310 the polymeric material 320 is shaped to bemounted to an eye of a wearer of the body-mountable device 310. Thepolymeric material 320 can be a substantially transparent material toallow incident light to be transmitted to an eye while thebody-mountable device 310 is mounted to the eye. The polymeric material320 can be a biocompatible material similar to those employed to formvision correction and/or cosmetic contact lenses in optometry, such aspolyethylene terephthalate (“PET”), polymethyl methacrylate (“PMMA”),silicone hydrogels, combinations of these, etc. The polymeric material320 can be formed with one side having a concave surface 326 suitable tofit over a corneal surface of an eye. The opposing side of the disk canhave a convex surface 324 that does not interfere with eyelid motionwhile the eye-mountable device 310 is mounted to the eye. A circularouter side edge 328 connects the concave surface 324 and convex surface326.

The body-mountable device 310 can have dimensions similar to visioncorrection and/or cosmetic contact lenses, such as a diameter ofapproximately 1 centimeter, and a thickness of about 0.1 to about 0.5millimeters. However, the diameter and thickness values are provided forexplanatory purposes only. In some embodiments, the dimensions of thebody-mountable device 310 can be selected according to the size and/orshape of the corneal surface of the wearer's eye.

The polymeric material 320 can be formed with a curved shape in avariety of ways. For example, techniques similar to those employed toform vision-correction contact lenses, such as heat molding, injectionmolding, spin casting, etc. can be employed to form the polymericmaterial 320. While the body-mountable device 310 is mounted in an eye,the convex surface 324 faces outward to the ambient environment whilethe concave surface 326 faces inward, toward the corneal surface. Theconvex surface 324 can therefore be considered an outer, top surface ofthe eye-mountable device 310 whereas the concave surface 326 can beconsidered an inner, bottom surface. The “bottom” view shown in FIG. 3Ais facing the concave surface 326. From the bottom view shown in FIG.3A, the outer periphery 322, near the outer circumference of the curveddisk is curved out of the page, whereas the center region 321, near thecenter of the disk is curved in to the page.

A base 330 is embedded in the polymeric material 320. The base 330 canbe embedded to be situated along the outer periphery 322 of thepolymeric material 320, away from the center region 321. The base 330does not interfere with vision because it is too close to the eye to bein focus and is positioned away from the center region 321 whereincident light is transmitted to the eye-sensing portions of the eye.Moreover, the base 330 can be formed of a transparent material tofurther mitigate any effects on visual perception.

The base 330 can be shaped as a flat, circular ring (e.g., a disk with acentral hole). The flat surface of the base 330 (e.g., along the radialwidth) is a platform for mounting a battery 360 and/or for mountingelectronics such as chips (e.g., via flip-chip mounting) and forpatterning conductive materials (e.g., via deposition techniques) toform electrodes, antenna(e), and/or connections. The base 330 and thepolymeric material 320 can be approximately cylindrically symmetricabout a common central axis. The base 330 can have, for example, adiameter of about 10 millimeters, a radial width of about 1 millimeter(e.g., an outer radius 1 millimeter greater than an inner radius), and athickness of about 50 micrometers. However, these dimensions areprovided for example purposes only, and in no way limit the presentdisclosure. The base 330 can be implemented in a variety of differentform factors.

A loop antenna 370, controller 350, and battery 360 are disposed on theembedded base 330. The controller 350 can be a chip including logicelements configured to operate the loop antenna 370 and to be at leastpartially powered by the battery 360. The controller 350 could also beconfigured to recharge the battery 360. The controller 350 iselectrically connected to the loop antenna 370 by interconnects 357 alsosituated on the base 330. Similarly, the controller 350 is electricallyconnected to the battery 360 by an interconnect 351. The interconnects351, 357, the loop antenna 370, and any conductive electrodes (e.g., foran electrochemical analyte sensor, a charging port, etc.) can be formedfrom conductive materials patterned on the base 330 by a process forprecisely patterning such materials, such as deposition, lithography,etc. The conductive materials patterned on the base 330 can be, forexample, gold, platinum, palladium, titanium, carbon, aluminum, copper,silver, silver-chloride, conductors formed from noble materials, metals,combinations of these, etc.

As shown in FIG. 3A, which is a top view of the body-mountable device310, the battery 360 is mounted to a side of the base 330 facing theconcave surface 326. However, the battery, electronics, othercomponents, etc. situated on the base 330 can be mounted to either the“inward” facing side (e.g., situated closest to the concave surface 326)or the “outward” facing side (e.g., situated closest to the convexsurface 324). Moreover, in some embodiments, some components can bemounted and/or patterned on one side of the base 330, while othercomponents are mounted and/or patterned on the opposing side, andconnections between the two can be made via conductive materials passingthrough the base 330.

The loop antenna 370 can be a layer of conductive material patternedalong the flat surface of the substrate to form a flat conductive ring.In some instances, the loop antenna 370 can be formed without making acomplete loop. For instance, the antenna 370 can have a cutout to allowroom for the controller 350 and battery 360, as illustrated in FIG. 3A.However, the loop antenna 370 can also be arranged as a continuous stripof conductive material that wraps entirely around the flat surface ofthe base 330 one or more times. For example, a strip of conductivematerial with multiple windings can be patterned on the side of the base330 opposite the controller 350 and battery 360. Interconnects betweenthe ends of such a wound antenna (e.g., the antenna leads) can be passedthrough the base 330 to the controller 350.

FIG. 3C is a side cross-section view of the example body-mountabledevice 310 while mounted to a corneal surface 22 of an eye 10. FIG. 3Dis a close-in side cross-section view enhanced to show the tear filmlayers 40, 42 surrounding the exposed surfaces 324, 326 of the examplebody-mountable device 310. FIG. 3D additionally shows the configurationof the battery 360 including a substrate 361, electrolyte 362, anode364, cathode 366, and biocompatible protective layer 368. It is notedthat relative dimensions in FIGS. 3C and 3D are not necessarily toscale, but have been rendered for purposes of explanation only indescribing the arrangement of the example body-mountable device 310. Forexample, the total thickness of the body-mountable device 310 can beabout 200 micrometers, while the thickness of the tear film layers 40,42 can each be about 10 micrometers, although this ratio may not bereflected in the drawings. Further, the battery 360 can have an overallthickness (defined by respective thicknesses of the substrate 361, thebiocompatible protective layer 368, and a thickest portion of theelectrolyte 362, cathode 366, and anode 364 between the substrate 361and the biocompatible protective layer 368) that is less than about 50microns, although this measurement may not be reflected in the drawings.Some aspects are exaggerated to allow for illustration and facilitateexplanation.

The eye 10 includes a cornea 20 that is covered by bringing the uppereyelid 30 and lower eyelid 32 together over the top of the eye 10.Incident light is received by the eye 10 through the cornea 20, wherelight is optically directed to light sensing elements of the eye 10(e.g., rods and cones, etc.) to stimulate visual perception. The motionof the eyelids 30, 32 distributes a tear film across the exposed cornealsurface 22 of the eye 10. The tear film is an aqueous solution secretedby the lacrimal gland to protect and lubricate the eye 10. When thebody-mountable device 610 is mounted in the eye 10, the tear film coatsboth the concave and convex surfaces 324, 326 with an inner layer 40(along the concave surface 326) and an outer layer 42 (along the convexlayer 324). The tear film layers 40, 42 can be about 10 micrometers inthickness and together account for about 10 microliters.

The tear film layers 40, 42 are distributed across the corneal surface22 and/or the convex surface 324 by motion of the eyelids 30, 32. Forexample, the eyelids 30, 32 raise and lower, respectively, to spread asmall volume of tear film across the corneal surface 22 and/or theconvex surface 324 of the body-mountable device 310. The tear film layer40 on the corneal surface 22 also facilitates mounting thebody-mountable device 310 by capillary forces between the concavesurface 326 and the corneal surface 22. In some embodiments, thebody-mountable device 310 can also be held over the eye in part byvacuum forces against corneal surface 22 due to the concave curvature ofthe eye-facing concave surface 326.

As shown in the cross-sectional views in FIGS. 3C and 3D, the base 330can be inclined such that the flat mounting surfaces of the base 330 areapproximately parallel to the adjacent portion of the concave surface326. As described above, the base 330 is a flattened ring with aninward-facing surface 332 (closer to the concave surface 326 of thepolymeric material 320) and an outward-facing surface 334 (closer to theconvex surface 324). The base 330 can have batteries, electroniccomponents, and/or patterned conductive materials mounted to either orboth mounting surfaces 332, 334. As shown in FIG. 3D, the battery 360,controller 350, and conductive interconnect 351 are mounted on theoutward-facing surface 334. However, in other examples, the battery 360and/or other components may be mounted on the inward-facing surface 332of the base 330.

The battery 360 includes a substantially planar substrate 361, anelectrolyte 362 disposed on the substrate 361, a cathode 364 disposed onthe substrate 361, an anode 366 disposed on the substrate 361, and abiocompatible protective layer 368 disposed to cover the electrolyte 362and at least a portion of both the cathode 364 and the anode 366. Thebiocompatible protective layer 368 additionally covers other componentsdisposed on the outward-facing surface 334 of the base 330 including thecontroller 360, the loop antenna 370 and the interconnects 351, 357. Theelectrolyte 362 has a first surface 363 and a second surface 365extending from the substrate 361. The second surface 365 is opposite thefirst surface 363. The cathode 364 is in contact with the first surface363 of the electrolyte 362 and the anode 366 does not overlap thecathode 364 and is in contact with the second surface 365 of theelectrolyte 362.

The components of the battery 360 could be configured according to anapplication. In some examples, the substrate 361 could be glass,silicon, diamond, silicon carbide, or some other material. Thebiocompatible protective layer 368 could be configured to prevent thetear fluid of the eye from degrading the function of the battery. Forexample, the biocompatible protective layer could be a layer of parylenedeposited onto the substrate, anode, cathode, and/or electrolyte andcured to form a biocompatible moisture barrier. Adhesion promoters couldalso be included in the biocompatible protective layer 368.

The electrolyte 362, cathode 364, and anode 366 could include variousmaterials in various configurations such that the electrochemicalbattery 360 could provide power to the body-mountable device 310. Forexample, the electrolyte 362 could be a gel polymer, a liquid, a solid,a ceramic, or some other material. In some examples, the electrolyte 362could be a gel polymer including polyacrylonitrile, propylene carbonate,ethylene carbonate, and zinc trifluoromethane sulfonate. In someexamples, the anode 366 could include zinc metal on a surface of theanode 366 in contact with the electrolyte 362, and the cathode 364 couldinclude manganese oxide on a surface of the cathode 364 in contact withthe electrolyte 362. Further, first and second surfaces 363, 365 of theelectrolyte 362 could be separated by a distance of about 100 microns.

In the illustrated example body-mountable device 310, the battery 360 isconfigured to be rectangular and the electrolyte 362 has first andsecond surfaces 363, 365 extending from the substrate 361 that aresubstantially planar. This is meant as a non-illustrative example only.A battery included in the body-mountable device 310 could be configuredto have a variety of shapes. For example, the electrolyte could becurved shapes, closed loops, branching structures, space-filling curves,angular shapes, and/or other configurations according to an application.More than one battery could be disposed in the body-mountable device.One or more batteries could be mounted on either or both mountingsurfaces 332, 334.

A battery disposed in the body-mountable device 310 could be configuredto have a central hole or transparent region such that, when the batterywas disposed in the body-mountable device 310 such that the hole ortransparent region of the battery was overlapping with the center region321, light could pass through the hole or transparent region of thebattery, through the center region 321 of the body-mountable device 310,to the eye 10. In some examples, the body-mountable device could includea battery having an electrolyte configured as a closed loop (similar tothe battery 200 d illustrated in FIG. 2D) disposed on the base 330. Insome examples, the body-mountable device could include a batteryconfigured as an angled or smooth spiral (similar to the batteries 200C,200 e illustrated in FIGS. 2C and 2E). In some examples, the spiralcould have an open and/or transparent center region and could bedisposed on the base 330 such that the center region of the batteryoverlapped with the center region 321 of the body-mountable device 310.Other configurations of a battery encircling a central transparentregion of a body-mountable device are anticipated.

An electrochemical battery included in the body-mountable device 310could include more than one electrochemical cell. For example thebattery could include a second electrolyte disposed on the substrate ofthe battery and having a first surface and a second surface extendingfrom the substrate. The second surface could be opposite the firstsurface. The battery could additionally a second cathode disposed on thesubstrate (that is in contact with the first surface of the secondelectrolyte), and a second anode (that does not overlap the secondcathode and that is in contact with the second surface of the secondelectrolyte). The biocompatible protective of the battery couldadditionally cover the second electrolyte and at least portions of thesecond cathode and the second anode. The battery could include more thantwo cells. Individual cells of the battery could be configured similarly(e.g., different cells could have electrolytes, cathodes, and/or anodesmade of similar materials) or differently according to an application.Different cells of a battery could be connected to each other and tocomponents of the body-mountable device 310 in a variety a ways (e.g.,in parallel, in series) according to an application.

A battery included in a body-mountable device could be operatedaccording to a variety of applications. In some examples, the batterycould be used to power a controller, a sensor, a light emitter, or someother system of the body-mountable device. In some examples, some otherpower source in the body-mountable device (e.g., a solar cell, an RFenergy receiving antenna) could partially power the body-mountabledevice at the same time as the battery. Additionally or alternatively,the battery could power the body-mountable device during some periods oftime, while another power source could power the body-mountable deviceduring other periods of time. For example, an RF energy receivingantenna could power the body-mountable device when the body-mountabledevice was proximate to a source of RF energy and the battery couldpower the body-mountable device when the body-mountable device was notproximate to a source of RF energy. The battery could be operated toprovide backup power (e.g., to save information stored in a volatilememory or to maintain a diminished level of operation of thebody-mountable device) when a primary source of power for thebody-mountable device was not available.

A battery included in a body-mountable device could be configured to berechargeable. Such a rechargeable battery could be alternativelydischarged to power the body mountable device and recharged by thebody-mountable device or some other system when another source of energyis available. The battery could be recharged using energy received usingan RF energy receiving antenna, solar cell, or some other sourcedisposed in the body-mountable device. Additionally or alternatively,the body-mountable device could be configured to receive energy forrecharging a battery by direct physical contact with a rechargingdevice. For example, the body-mountable device could include two or moreelectrical contacts configured to be in electrical contact with a powersource such that the rechargeable battery could be recharged using powertransmitted though the at least two electrical contacts.

A body-mountable device could include additional components that couldbe powered by the battery to perform some function. In some examples,the body-mountable device could include a chemical sensor. The chemicalsensor could be configured to detect the presence and/or concentrationof a chemical in an environment of the body-mountable device. Forexample, the body-mountable device could be configured to be mounted toa surface of an eye, and the chemical sensor could be configured todetect the concentration of a chemical in a tear fluid of the eye (forexample, glucose). In some examples, the body-mountable device couldcontain light emitters or other means for controlling and/or emittingpatterned energy. For example, the body-mountable device could beconfigured to be mounted to an eye, and the body-mountable device couldinclude an array of light emitters and optics such that thebody-mountable device could be operated to present a display image tothe eye. Other components and applications of a body-mountable deviceare anticipated.

The example body-mountable devices of FIGS. 3A-3D illustrate exampleembodiments of body-mountable devices incorporating batteries configuredto at least partially power components of the example body-mountabledevices. The example embodiments are meant as non-limiting examples andother embodiments are anticipated. For example, body-mountable devicesincorporating batteries could be configured to be mounted on a tooth, ina mouth, on a skin surface, or on some other accessible part of a body.A body-mountable device incorporating a battery could be configured suchthat it lacked one or more of the components included in the examplebody-mountable device 310 (e.g., the base 330, controller 350, the loopantenna 370, etc.). For example, a body-mountable device could containonly an electrochemical battery as disclosed herein and a simpleelectronic component electronically coupled to the battery (e.g., alight emitting diode, an iontophoretic chamber containing a chargedpharmaceutical or other chemical, or some other component).

Moreover, it is particularly noted that while embodiments are describedherein by way of example as a body-mountable device or an ophthalmicdevice including a battery embedded in a shaped polymeric material, thedisclosed electrochemical battery therefore can be applied in othercontexts as well. For example, electrochemical batteries disclosedherein may be included in wearable (e.g., body-mountable) and/orimplantable devices. In some contexts, a battery is situated to besubstantially encapsulated by bio-compatible polymeric material suitablefor being in contact with bodily fluids and/or for being implanted. Inone example, a mouth-mountable device includes a battery and isconfigured to be mounted within an oral environment, such as adjacent atooth or adhered to an inner mouth surface. In another example, animplantable medical device that includes a battery may be encapsulatedin biocompatible material and implanted within a host organism. Suchbody-mounted and/or implanted devices can include circuitry configuredto operate a light sensor and/or light emitter by providing power to thesensor and/or emitter from the battery and measuring a resultingcurrent, voltage, or other electronic variable. The device can alsoinclude an energy harvesting system and a communication system forwirelessly indicating sensor results (e.g., measured current) and/orrecharging the battery. In other examples, batteries disclosed hereinmay be included in wireless sensors which are not used to makemeasurements in or on a human body. For example, batteries disclosedherein may be included in body-mountable and/or implantable sensors usedto measure a property of a fluid of an animal. In another example,batteries disclosed herein may be included in devices to measure aproperty of an environment, such as a river, lake, marsh, reservoir,water supply, sanitary sewer system, or storm sewer system. In anotherexample, batteries disclosed herein may be included in devices tomeasure a property of a fluid which is part of a process, such as awaste treatment process, pharmaceutical synthesis process, foodpreparation process, fermentation process, or medical treatment process.

IV. Example Fabrication Method

FIG. 4 is a flowchart of an example process 400 for fabricating anelectrochemical battery. A substantially planar substrate is formed(402) to provide a base structure for the fabrication of the device. Thesubstrate material could be glass, silicon, diamond, silicon carbide, orsome other material according to an application. The substrate could beformed by a variety of methods related to the substrate material. Forexample, the substrate could be formed through casting, machining,epitaxial crystal growth, CVD, PVD, polymerization, electroplating, orsome other method.

An electrolyte is formed on the substrate, such that the electrolyte hasa first surface extending from the substrate and a second surfaceextending form the substrate and opposite the first face (404). Theformed electrolyte could include amorphous, crystalline,polycrystalline, and/or polymeric solid or gel components. Theelectrolyte could also include liquid components. The formed electrolytecould include organic and/or inorganic salts, metallic or nonmetallicions, solvents, and/or dissolved gases. Some components (e.g., salts)could be dissolved in other components of the formed electrolyte (e.g.,a flexible lattice of a gel polymer, a solid polymer, or a ceramic). Insome examples, the formed electrolyte is a gel electrolyte and the gelelectrolyte includes polyacrylonitrile, propylene carbonate, ethylenecarbonate, and zinc trifluoromethane sulfonate. Other electrolytechemistries and configurations could be used.

Forming the electrolyte could include forming the electrolyte to have aspecified shape and/or size. In some examples, the formed electrolytecould have a closed shape. For example, the electrolyte could be formedas a closed loop or ellipse. Additionally or alternatively, the formedelectrolyte could have a branching and/or space-filling shape, whereinthe formed electrolyte could have multiple ‘first surfaces’ and multiple‘second surfaces’ such that first and second surfaces are locallysubstantially opposite. The electrolyte could be formed to have someother shape or shapes. A feature of the formed electrolyte (e.g., athickness of the electrolyte) could be specified to optimize an energycapacity, a power capacity, a current capacity, a cost, and/or someother factor or property of a battery formed in part by forming theelectrolyte.

Forming the electrolyte could include a variety of processes orcombinations of processes. For example, forming the electrolyte couldinclude CVD, PVD, spin-casting, UV curing, heat curing,photopolymerization, chemically-initiated polymerization, adsorption,absorption, screen printing, inkjet printing, photolithography, or othermethods. In some examples, forming the electrolyte could include forminga solid or a gel structure. In some examples, forming the electrolytecould include adding a component of the electrolyte to an already-formedcomponent of the electrolyte. Other methods and combinations of methodsare anticipated.

A cathode is formed on the substrate, such that the cathode is incontact with the first surface of the electrolyte (406). The formedcathode could include a variety of materials or combinations ofmaterials. For example, the cathode could include metals, conductivepolymers, crystals, nanotubes, nanomaterials, oxides, or othermaterials. For example, the cathode could include copper, zinc, lithium,aluminum, nickel, lead, iron, silver, gold, metal oxides, metal salts,metal alloys, doped polypyrrole, graphite, or some other material ormaterials. A cathode could be formed through a variety of methods orcombinations of methods. For example, method of forming a cathode couldinclude CVD, PVD, sputtering, spin-casting, UV curing, heat curing,photopolymerization, chemically-initiated polymerization, screenprinting, inkjet printing, photolithography, crystallization, annealing,or other methods. The cathode could be formed with multiple materials.For example, the bulk of a formed cathode could include a bulk metal(e.g., aluminum) while a surface of the formed cathode could includemanganese oxide. In some examples, forming the cathode could involvemultiple processes. For example, the bulk of a formed cathode could beformed by PVD and photolithography, and a surface of the formed cathodecould include a manganese oxide layer formed by spray deposition,electroplating, CVD, plasma oxidation or some other method. Othermethods and combinations of methods are anticipated.

An anode is formed on the substrate, such that the anode is in contactwith the second surface of the electrolyte, and the anode and cathodeare non-overlapping (408). The formed cathode could include a variety ofmaterials or combinations of materials. For example, the anode couldinclude metals, conductive polymers, crystals, nanotubes, nanomaterials,oxides, or other materials. For example, the anode could include copper,zinc, lithium, aluminum, nickel, lead, iron, silver, gold, metal oxides,metal salts, metal alloys, doped polypyrrole, graphite, or some othermaterial or materials. For example, the anode could be a zinc foil ordeposited zinc film. The anode could be formed with multiple materials.An anode could be formed through a variety of methods or combinations ofmethods. For example, method of forming an anode could include CVD, PVD,sputtering, spin-casting, UV curing, heat curing, photopolymerization,chemically-initiated polymerization, screen printing, inkjet printing,photolithography, crystallization, annealing, or other methods. Othermethods and combinations of methods are anticipated.

A biocompatible protective layer is formed, such that the biocompatibleprotectively layer covers the electrolyte and at least portions of thecathode and the anode (410). The biocompatible protective layer could beformed to cover additional structures. The formed biocompatibleprotective layer could include a variety of materials or combinations ofmaterials. For example, the biocompatible protective layer could includemetals, polymers, nanomaterials, or other materials. For example, thebiocompatible protective layer could include polyanhydride, calciumhydroxylapatite, PTFE, parylene, silicone, silicon, glass, stainlesssteel, titanium, or some other material. Forming a biocompatibleprotective layer could include applying a surface treatment or applyinga surface coating to a base material. For example, proteins could beadsorbed or otherwise bound to a surface of a material of thebiocompatible protective layer. A biocompatible protective layer couldbe formed through a variety of methods or combinations of methods. Forexample, method of forming a biocompatible protective layer couldinclude CVD, PVD, sputtering, spin-casting, UV curing, heat curing,photopolymerization, chemically-initiated polymerization, screenprinting, inkjet printing, photolithography, plasma processing,crystallization, or other methods. Other methods and combinations ofmethods are anticipated.

The process 400 for fabricating an electrochemical battery could includeadditional steps. In some examples, the process 400 could include atleast partially embedding the substrate and components disposed thereon(e.g., the electrolyte, the anode, the cathode) in a shaped polymericmaterial. The shaped polymeric material could have a concave surface anda convex surface, wherein the concave surface is configured to beremovably mounted over a corneal surface of an eye and the convexsurface is configured to be compatible with eyelid motion when theconcave surface is so mounted. The shaped polymeric material could be asubstantially transparent material to allow incident light to betransmitted to an eye. The polymeric material could be a biocompatiblematerial similar to those employed to form vision correction and/orcosmetic contact lenses in optometry, such as polyethylene terephthalate(“PET”), polymethyl methacrylate (“PMMA”), silicone hydrogels,combinations of these, etc. The shaped polymeric material could beformed in a variety of ways. For example, techniques similar to thoseemployed to form vision-correction contact lenses, such as heat molding,injection molding, spin casting, etc. can be employed to form the shapedpolymeric material.

In some examples, the process 400 could include disposing the substrateand components disposed thereon (e.g., the electrolyte, the anode, thecathode) in a device with other components. The other components couldinclude electronics, sensors, interconnects, conductive traces, wires,or other elements. The substrate could be mounted to a housing, a base,a printed circuit board, or some other element. The anode and/or cathodecould be connected to other elements (e.g., electronics, wires,conductive traces) by a variety of methods. For example, the anodeand/or cathode could be connected to other elements by welding,press-fitting, applying a conductive material (e.g., a conductiveadhesive, epoxy, gel, and/or polymer), soldering, sputtering, CVD, PVDor some other method. Additionally or alternatively, some components(e.g., electronics, conductive traces) could be formed and/or disposedon the substrate.

In some examples, the process 400 could include forming more than oneelectrolyte, anode, and/or cathode. The more than one electrolyte,anode, and/or cathode could be formed similarly or differently. The morethan one electrolyte, anode, and/or cathode could be formed at the sametime or as port of different steps separated in time. The process 400could further include forming interconnects between the multiple anodesand/or cathodes such that the multiple formed electrochemical cells (anelectrochemical cell including a single electrolyte and correspondinganode(s) and cathode(s)) were electrically connected in series, inparallel, or according to some other configuration.

Note that the ordering of the steps of the example process 400 is meantas an illustrative example and not meant to be limiting. An ordering ofsteps of the process 400 could be chosen based on properties of theindividual steps of the process 400. For example, forming a cathode 406could include an annealing process occurring at a first temperature.Forming an electrolyte 404 could include forming an electrolyte that wasdamaged by temperatures exceeding a second temperature, where the secondtemperature was less than the first temperature. In such an example, theannealing process of forming a cathode 406 could occur before forming anelectrolyte 404. Other processes and process considerations arepossible. Thus, other ordering of the steps of the process 400 areanticipated.

CONCLUSION

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

Further, where example embodiments involve information related to aperson or a device of a person, some embodiments may include privacycontrols. Such privacy controls may include, at least, anonymization ofdevice identifiers, transparency and user controls, includingfunctionality that would enable users to modify or delete informationrelating to the user's use of a product.

In situations in where embodiments discussed herein collect personalinformation about users, or may make use of personal information, theusers may be provided with an opportunity to control whether programs orfeatures collect user information (e.g., information about a user'smedical history, social network, social actions or activities,profession, a user's preferences, or a user's current location), or tocontrol whether and/or how to receive content from a content server thatmay be more relevant to the user. In addition, certain data may betreated in one or more ways before it is stored or used, so thatpersonally identifiable information is removed. For example, a user'sidentity may be treated so that no personally identifiable informationcan be determined for the user. Thus, the user may have control overwhether and how information about the user is collected and used.

What is claimed is:
 1. A battery, comprising: a substrate; anelectrolyte disposed on the substrate, wherein the electrolyte has afirst surface extending from the substrate and a second surfaceextending from the substrate and opposite the first surface, wherein thefirst and second surfaces of the electrolyte are less than about 100microns apart; a cathode disposed on the substrate and in contact withthe first surface of the electrolyte; an anode disposed on the substrateand in contact with the second surface of the electrolyte, wherein theanode and cathode are non-overlapping; and a biocompatible protectivelayer, wherein the biocompatible protective layer covers the electrolyteand at least portions of the cathode and anode.
 2. The battery of claim1, wherein the battery has an overall thickness defined by respectivethicknesses of the substrate, the biocompatible protective layer, and athickest portion of the electrolyte, cathode, and anode between thesubstrate and the biocompatible protective layer, wherein the overallthickness is less than about 50 microns.
 3. The battery of claim 1,wherein the biocompatible protective layer comprises parylene.
 4. Thebattery of claim 1, wherein the substrate comprises silicon.
 5. Thebattery of claim 1, wherein the electrolyte comprises a gel polymer. 6.The battery of claim 5, wherein the gel polymer comprisespolyacrylonitrile, propylene carbonate, ethylene carbonate, and zinctrifluoromethane sulfonate.
 7. The battery of claim 1, furthercomprising: a second electrolyte disposed on the substrate, wherein thesecond electrolyte has a first surface extending from the substrate anda second surface extending from the substrate and opposite the firstsurface; a second cathode disposed on the substrate and in contact withthe first surface of the second electrolyte; and a second anode disposedon the substrate and in contact with the second surface of the secondelectrolyte, wherein the second anode and second cathode arenon-overlapping; wherein the biocompatible protective layer additionallycovers the second electrolyte and at least portions of the secondcathode and second anode.
 8. The battery of claim 1, wherein theelectrolyte is configured as a closed loop.
 9. The battery of claim 1,wherein the electrolyte has a spiral shape.
 10. A body-mountable devicecomprising: a shaped polymeric material; and a battery embedded withinthe shaped polymeric material, wherein the battery comprises: asubstrate; an electrolyte disposed on the substrate, wherein theelectrolyte has a first surface extending from the substrate and asecond surface extending from the substrate and opposite the firstsurface, wherein the first and second surfaces of the electrolyte areless than about 100 microns apart; a cathode disposed on the substrateand in contact with the first surface of the electrolyte; an anodedisposed on the substrate and in contact with the second surface of theelectrolyte, wherein the anode and cathode are non-overlapping; and abiocompatible protective layer, wherein the biocompatible protectivelayer covers the electrolyte and at least portions of the cathode andanode.
 11. The body-mountable device according to claim 10, furthercomprising electronics embedded in the shaped polymeric material. 12.The body-mountable device according to claim 10, wherein the shapedpolymeric material has a concave surface that can be removably mountedover a corneal surface of an eye and a convex surface opposite theconcave surface.
 13. The body-mountable device of claim 10, wherein thebattery has an overall thickness defined by respective thicknesses ofthe substrate, the biocompatible protective layer, and a thickestportion of the electrolyte, cathode, and anode between the substrate andthe biocompatible protective layer, wherein the overall thickness isless than about 50 microns.
 14. The body-mountable device of claim 10,wherein the electrolyte comprises a gel polymer.
 15. The body-mountabledevice of claim 14, wherein the gel polymer comprises polyacrylonitrile,propylene carbonate, ethylene carbonate, and zinc trifluoromethanesulfonate.
 16. The body-mountable device of claim 10, wherein thebiocompatible protective layer comprises parylene.
 17. Thebody-mountable device of claim 10, wherein the battery furthercomprises: a second electrolyte disposed on the substrate, wherein thesecond electrolyte has a first surface extending from the substrate anda second surface extending from the substrate and opposite the firstsurface; a second cathode disposed on the substrate and in contact withthe first surface of the second electrolyte; and a second anode disposedon the substrate and in contact with the second surface of the secondelectrolyte, wherein the second anode and second cathode arenon-overlapping; wherein the biocompatible protective layer additionallycovers the second electrolyte and at least portions of the secondcathode and second anode.
 18. A method comprising: forming a substrate;forming an electrolyte on the substrate, such that the electrolyte has afirst surface extending from the substrate and a second surfaceextending from the substrate and opposite the first surface, wherein thefirst and second surfaces of the electrolyte are less than about 100microns apart; forming a cathode on the substrate, such that the cathodeis in contact with the first surface of the electrolyte; forming ananode on the substrate, such that the anode is in contact with thesecond surface of the electrolyte, and the anode and cathode arenon-overlapping; and forming a biocompatible protective layer, such thatthe biocompatible protective layer covers the electrolyte and at leastportions of the cathode and anode.
 19. The method of claim 18, furthercomprising at least partially embedding the substrate and componentsdisposed thereon in a shaped polymeric material, wherein the shapedpolymeric material has a concave surface that can be removably mountedover a corneal surface of an eye and a convex surface opposite theconcave surface.